21210231191 has 2 divisors, whose sum is σ = 21210231192. Its totient is φ = 21210231190.

The previous prime is 21210231187. The next prime is 21210231209. The reversal of 21210231191 is 19113201212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21210231191 - 2² = 21210231187 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21210231121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605115595 + 10605115596.

It is an arithmetic number, because the mean of its divisors is an integer number (10605115596).

Almost surely, 2^21210231191 is an apocalyptic number.

21210231191 is a deficient number, since it is larger than the sum of its proper divisors (1).

21210231191 is an equidigital number, since it uses as much as digits as its factorization.

21210231191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 23.

The spelling of 21210231191 in words is "twenty-one billion, two hundred ten million, two hundred thirty-one thousand, one hundred ninety-one".